The present invention generally relates to a workstation having a work surface table and, more particularly, to a motorized height adjustable table assembly and control system therefor.
Conventional workstations exist which have a height adjustable work surface, i.e., table, to accommodate different users and for different uses. For example, adjustable height tables are commonly made available for supporting computers and their accessories. Some conventional height adjustable tables have employed a mechanical adjustment assembly which allows for the work surface to be manually raised and lowered in height. The mechanical height adjustment assembly generally includes a manually-operated hand crank connected to a shaft and gear assemblies at opposite ends of the table, which are often driven together by a cross-connected shaft. The mechanical drive assembly, particularly the hand crank, generally consumes a large amount of space, can be difficult to operate, and often interferes with the use of the workstation.
Conventional workstation tables have also employed an electric motor for power assistance to adjust the height of the work surface. In one approach, the motor is generally configured to drive a cross-connected linkage connecting opposite ends of the table, and thereby requires a complex mechanical assembly. Another motorized approach is disclosed in U.S. Pat. No. 5,259,326 which discloses an automatic height adjustable workstation with a pair of motors for raising and lowering each table. The aforementioned multiple motor approach monitors the rotational speed of each drive arrangement and controls the motors by varying the speed of each motor to maintain a substantially level work surface. This approach requires a pulse width modulator for adjusting the speed of the motor to slow down a faster running motor to substantially equal the speed of the slower running motor. The required motor speed control, as well as required limit switches, add to the cost and complexity of the system. In addition, the aforementioned approach uses an in-line drive arrangement which requires the addition of a brake mechanism to prevent back driving of the work surface due to heavy loads. Accordingly, it is desirable to provide a motorized height adjustable table that is less expensive and easy to use.